Groucho Marx may have been among the greatest and most loved comics of the last century - in the late 1970s, NYU freshmen named him, along with Jesus and Albert Schweitzer, one of the three most admired men in history - but he was nonetheless, it turns out, not a nice man. Verbally abusive, emotionally hidden, typically using others as his straight man or fall guy, suspicious and pessimistic, he drove two wives and a daughter to alcohol. It is not so surprising, then, that he didn't like himself too much, either - that famous quip about not joining any club that would have him as a member was no joke.

Stefan Kanfer's biography admirably combines the various sides of Groucho's career and personality into an absorbing narrative, one generously sprinkled with excerpts from Marx Brothers scripts, Groucho's quips and the elaborate practical jokes they played on friends and colleagues. (Example: On a road trip, they one night convinced hotel security personnel that Margaret Dumont, who played the stately dowager and Groucho's foil in many of their films, was actually a prostitute. Groucho made the complaint that she had taken his money and failed to provide, Zeppo soon thereafter emerged from her closet wrapped in a hotel towel and then, the coup de grace, Harpo rose nude from her bathtub and glided silently out of the room with a necktie elegantly fastened around his genitals.)

Born in 1890, Julius was intelligent, withdrawn, jealous of his brothers and dominated by his mother Minnie, who forced him to leave school at age 13 and then, along with elder brothers Leonard and Adolph, maneuvered him into a vaudeville career. Minnie had chutzpah, brains and a brother, Al Shean, half of the hit comedy team of Gallagher and Shean, who helped the brothers mold their act: Leonard as the Italian rascal, Adolph doing pantomimes, Julius as stand-up comic. A friend gave them stage names (Leonard became Chicko, because he was a compulsive woman-chaser, Adolph became Harpo for his instrument, and Julius, Groucho, for some combination of his personality and a chamois "grouch bag" in which he stored his valuables on the road. A typesetter dropped the k, Chico kept the change, and here they are, ladies and gentlemen, the Marx Brothers. (Brother Herbert, Zeppo the straight man, later dropped out of the act, and Milton, Gummo, hardly got in).

By the 1920s, the Marxes were successful in vaudeville, with their trademark style of farce and non sequitur already well developed, on stage and off. But vaudeville was dying and, after success on Broadway with "Animal Crackers" and "The Cocoanuts," which were later adapted into their first films, the brothers went to Hollywood. Money and fame were flowing their way. In quick succession came the film hits "Monkey Business," "Horse Feathers" and "Duck Soup," bringing the Marxian combination of irreverent mania to the masses, with Groucho perfecting his role as wise-cracking confidence man.

Iconoclastic and irascible (Groucho's words for himself), irreverent in real life as well as in film, anti-establishment "nihilists," as one reviewer called them, the Marxes, and Groucho in particular, established their personae as permanent outsiders, unassimilable outlanders living on their wits - luftmenschen. The line that Kanfer draws from Groucho to Woody Allen and Jerry Seinfeld might as easily join the Marxes to Abbie Hoffman - and it's no coincidence that all are Jews.

Though "A Night at the Opera," their next film, was another big hit, Kanfer makes the interesting point that something - whether success or MGM's Irving Thalberg, their producer - changed the brothers. "Instead of making sport of romance," writes Kanfer, "they now facilitated it. Instead of whacking away at the powerful institutions of government or the military or education, they battled the toothless enemy of grand opera .... The crew of maniacs had become hilarious but harmless uncles ... not outrageous anymore, only frivolous .... Their humor tamed, they were now fit for wide public consumption."

Though Groucho went on to greater fame, greater wealth, friendship with literary and entertainment luminaries (including T.S. Eliot, who was a fan), and a career that kept him in the public eye for decades more, "A Night at the Opera" might be considered the beginning of his long decline.

The films that followed were less popular, and Groucho's attempts at radio and then television were failures. By the 1940s, he was doing product endorsements, while his career as an entertainer flickered until he became host on the quiz show "You Bet Your Life." But even that gig seemed to many a come-down for the great Groucho (whose shotgun-style "ad-libs," it turns out, were heavily scripted). Even rehearsed, of course, the man was a genius: To a woman who said she had borne 10 children because she loved her husband, Groucho replied, "I love my cigar, too, but I don't keep it in my mouth all the time."

Kanfer's portrait of the private Groucho is painful. His first of three wives, Ruth, was an attractive and deferential gentile (the brothers in general saved their Judaism for funerals). Groucho treated her like a child, made her the butt of his jokes and the victim of his tirades, banished her from the table for sins real and imagined, insisted she get advance permission from him for any purchases, and generally browbeat and verbally abused her. Her response was booze and overeating.

Miserly and resentful, Groucho picked on underlings and servants too. Harpo's wife Susan later put it this way: "He destroys people's egos. If you're vulnerable, you have absolutely no protection from Groucho." Chico's daughter said that her uncle "succeeded in driving me away - just as he did most of those close to him."

At 80, Groucho was an old man with prostate and bladder problems, a history of strokes, decrepit, dependent and slightly out of control. After his public suggestion that President Nixon be assassinated resulted in an FBI investigation, his son Arthur proposed that Groucho needed a "keeper," and friends suggested Erin Fleming, the woman with whom Groucho would be linked, for better and worse, in his last years. Ambitious, cheeky, loyal and domineering, a bit like mother Minnie, perhaps, the 30-year-old Fleming controlled Groucho, pushed him into performances he lacked the strength for, worked hard to get him an honorary Academy Award.

In endless court proceedings over his estate after Groucho's death in 1977, she was portrayed as a gold-digger who drugged, took advantage of and verbally abused Groucho, and as the one person who made him happy. (Fleming lost the suits and ended up, at least by rumor, as a Hollywood bag lady.)

Kanfer's story-telling, engaging all the way through, sometimes lapses by being not quite clear enough about the dates of the events he is narrating. His armchair psychoanalyzing is often not fully convincing, but in general he doesn't insist on it. The volume contains an extended "recommended reading list," but one misses both a filmography or "performography" and, especially, a chronology of Groucho's life.

These are minor points. All in all, "Groucho," the book, is fun, troubling, sometimes heartrending, and a useful companion to the public Marx and his brothers. Or, as Groucho, the man, once said, "Outside of a dog, a book is man's best friend. Inside of a dog, it's too dark to read."